If choosing a bottle from the dozens of wines on the average supermarket shelves is daunting, picking one off a restaurant wine list is doubly so, with the added suspicion that you're paying considerably over the odds for the privilege of having someone pour it for you.

There's some basis for that. Wine accounts for half the value of sales in a restaurant, despite the fact that it needs no preparation and fewer staff to serve it than the food. On cheaper bottles, the mark-up is generally four times what the restaurant pays for it, and you're still expected to pay service on top.

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So how do you spot a good buy? Not necessarily by buying the cheapest wines on the list. Restaurants expect to sell most of the second to fourth wines in each section of their list (customers avoid the cheapest in case they're thought a cheapskate), so those tend to be the ones on which they make the biggest margin.

It also pays to avoid famous names. "A restaurant will often put less of a mark-up on wines it wants its customers to try than on those it knows will sell easily such as chablis or sancerre," wine consultant Peter McCombie says.

A rich, dark-fruited southern Italian red such as Grifone Primitivo from Puglia (£7.50, or £6.75 if you buy a case of 12, from Jascots, which supplies both consumers and restaurants; 13% abv) is likely to be a much better bet than a weedy, overpriced chianti, while a crisp picpoul de pinet from the south of France is far more enjoyable than a bland pinot grigio. Domaine Félines-Jourdan is a particular favourite. You can find the 2011 vintage (13.5% abv) for £7.50 from the Wine Society and £8.99 from the Oxford Wine Company, among other stockists.

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Look out, too, for grüner veltliner, a deliciously versatile Austrian dry white wine with a refreshing peppery twist, which works particularly well with the lighter dishes on a menu. If you're looking for a bottle to take to your local BYO, try the award-winning Domäne Wachau Terraces Grüner Veltliner 2011 (12% abv) that's currently on promotion at Waitrose at £7.39.

Hearty Languedoc and southern Rhône reds won't let you down. Appellations such as Minervois, Faugères and Costières de Nîmes are worth looking out for, as are lesser-known Spanish reds such as Bierzo, Toro and Utiel-Requena.

And if you want to check how much a restaurant is adding on, there's a handy app called Wine Search (£1.49) that gives the retail price of the wine you're ordering.